1. Field of the Invention
The present invention relates generally to an apparatus and method for producing and discharging a mixture of a flowing fluid with a predetermined amount of an additive liquid, and more specifically, the present invention relates to a dispensing assembly and method for spraying water containing a metered amount of an additive liquid.
2. Description of the Prior Art
In many instances, it is desired to insert a metered amount of an additive liquid into a flowing fluid, which may also be a liquid (e.g., inserting an insecticide into water being sprayed on plants). In many such cases, again using the insecticide as an example, the additive liquid may be poisonous or otherwise dangerous or harmful. In such a case, a less concentrated form of the additive liquid may be used to minimize the risks occurring from any leakage or other discharge of the additive liquid without a sufficient amount of flowing water to dilute it at the time of discharge. Such an approach has the obvious disadvantages of increasing the amount of additive liquid that must be utilized for a particular purpose, with the attendant increase in cost and the inconvenience of shipping and storing the diluted additive liquid. The necessity of using large amounts of the additive liquid usually increases the problems of dispensing the resultant mixture.
If concentrated additive liquid is utilized, the dispensing assembly periodically requires recharging or refilling of the additive liquid supply in the dispensing assembly. To achieve the transfer of additive liquid from the storage container to the dispensing assembly requires much care to avoid exposing the user to considerable risk. In addition, the storage of the concentrated additive liquid creates the risk of inadvertent discharge of the liquid, such as by a child, with the resultant possibility of harmful exposure.
In dealing with harmful additive liquids, another potential threat is the possibility that additive liquid will remain in the dispensing assembly after usage, so that upon the next usage this undiluted additive liquid will present the risk of harm to either the user or the objects being sprayed. In devices utilizing the pressure of the flowing liquid to force out the additive liquid, a somewhat related danger is presented by the possibility of air pressure in the line forcing out the additive liquid before the flowing liquid is present to dilute the additive liquid.
Apart from the possible hazards, prior art devices exhibit many other deficiencies in operation. For example, many prior art devices work adequately for a particular additive liquid for which they have been designed, but utilization of an additive liquid having a different viscosity or other different material characteristics can result in the insertion of additive liquid amounts that are smaller or greater than desired. Also, most prior art devices are designed for a constant rate of flow of the flowing liquid. In a water line, the pressure variations will vary the rate of flow and hence the concentration of the mixture being sprayed will vary. Also, when the pressure of the flowing liquid is utilized to force out the additive liquid, it is necessary to prevent the flowing liquid from entering and diluting the additive liquid in the container prior to establishment of the pressure to force the additive liquid out. This can be achieved with appropriate valving, but if the proper steps are not followed, dilution of the additive liquid in the container may still follow. In addition, such valving requires either manual operation or complex automatic controls.
Other problems occur with respect to an indication of when the additive liquid container is empty. Various types of signaling approaches may be utilized, but a preferable approach would be to have the dispensing assembly automatically deactivated when the additive liquid has been completely used.